XJ 4.0 cutting out

77GreenMachine

77GreenMachine

Phillip Talton
Joined
Mar 30, 2010
Location
Trinity, NC
Stuck in a meeting till 3pm so I’m picking yalls brain.
94 XJ 4:88s and 35s Automatic
About 90k miles on engine.

When I go down the road and really get in the throttle in second gear, it starts cutting out. As if I was cycling the key on and off really fast. If I let off and roll the throttle it’s fine until I get around 3,000RPM. Anytime I start to really accelerate, it cuts out.
Now I would think fuel pump, except it was doing this before I changed the tank and sending unit (used) and still doing it now. It was also doing it before I regeared it.

Here’s the real question, I broke a rear drive shaft back in November. Ever since then my Speedo goes crazy, bouncing all over the place and pegs out jumping around. Is it possible that the jeep thinks I’m reaching max speed and it’s cutting the fuel? Not sure if this year even has such a thing.

I plan to change the fuel filter today. Wheeling this weekend and I anticipate some wet rev limiter action, I don’t need this thing cutting out while I’m trying to send it to climb a hill.

CPS is new, plugs & wires, cap, whole tune up done and not very old. Minus fuel filter.
 
Does it have a check engine light on? Those codes can be read with cycling the key 3 times if it does. The 94 will do that if the vacuum line to the map sensor is bad or cracked. I have seen mine run like crap with a cracked coil. I have seen others do that with a bad throttle position sensor. Definitely try the fuel filter though.
 
No CEL but I’d bet my paycheck there are several cracked vacuum line. I hadn’t even thought of that, I’ll check.

I though key cycling only working 97-99 then stopped after 2000.
 
Wiggle the wire going to the cps. I had 2 of them fail due to broke wires where they enter the sensor.
 
Also check the connector at the ignition coil. Yes it does have a speed limiter.. 117 if my memory is right. If you want, bring it by my shop in rutherfordton and I'll check it out, not sure how far you are away though. You can unplug the vss and see if it sets the speedometer at 0.. might be the ecm if it doesn't.
 
@a_kelley you are a good ride from me, I sure appreciate the offer though. I will check all of the above and also simply unplug the speed sensor on the Tcase and see what happens.
 
Got home and unplugged the speed sensor. Went down the road really sending it with zero sputters. However that causes the CEL to come on. Guess that pin points the issue and I will replace the sensor.
 
I think you can safely ignore the CEL... The vss isn't really used by the ECM, except for cruise, oh and the gauge. Might inspect the wiring for a broken wire also..
 
77GreenMachine said:
Got home and unplugged the speed sensor. Went down the road really sending it with zero sputters. However that causes the CEL to come on. Guess that pin points the issue and I will replace the sensor.
Click to expand...

I'm about 90% positive I have one if you want it.
 
@Chris_Keziah bring it with you this weekend. I pulled the sensor and cleaned it. It jumps around a lot less now and the sputtering is gone, but it may come back.

I forgot this particular case sat in my garage with no fluid in it for months, I think it just got some moisture in it and on the plug.

I’m also gonna need you to blow off work and come wheeling with me in the morning :driver:
 
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77GreenMachine said:
@Chris_Keziah bring tbwith you this weekend. I pulled the sensor and cleaned it. It jumps around a lot less now and the sputtering is gone, but it may come back.

I forgot this particular case sat in my garage with now fluid in it for months, I think it just got some moisture in it and on the plug.

I’m also gonna need you to blow off work and come wheeling with me in the morning :driver:
Click to expand...
My work calendar is full of meetings today and tomorrow, no way I'm getting ot of here.

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77GreenMachine said:
@Chris_Keziah bring tbwith you this weekend. I pulled the sensor and cleaned it. It jumps around a lot less now and the sputtering is gone, but it may come back.

I forgot this particular case sat in my garage with now fluid in it for months, I think it just got some moisture in it and on the plug.

I’m also gonna need you to blow off work and come wheeling with me in the morning :driver:
Click to expand...
I think I still have one on my 242. I can look tonight. I work in winston if that would be easy for you to get it.
 
Shoot I'm thinking about just working half a day tomorrow instead of going down. It looks like I'm the only one wanting to wheel in the morning and it wouldn't be smart to go wheel alone with it so slick and rainy.
 
77GreenMachine said:
Shoot I'm thinking about just working half a day tomorrow instead of going down. It looks like I'm the only one wanting to wheel in the morning and it wouldn't be smart to go wheel alone with it so slick and rainy.
Click to expand...

It could be the sensor or the gear inside the tailhousing. I stripped the teeth on the gear one time and it made the Speedo do all sort of wild movements. Just FYI


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